title: Laboratory diagnosis of paraneoplastic pemphigus.
abstract: BACKGROUND
  Paraneoplastic pemphigus (PNP) is a multiorgan disease characterized by antibodies against plakins, desmogleins and the α2-macroglobulin-like-1 (A2ML1) protein, in association with an underlying neoplasm. Accurate diagnosis relies on the demonstration of these autoantibodies in serum.
  
  
  OBJECTIVE
  To evaluate the value of different laboratory techniques in the serological diagnosis of PNP.
  
  
  METHODS
  We performed immunoblotting, envoplakin (EP) enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence (IIF) on rat bladder, radioactive immunoprecipitation and a nonradioactive combined immunoprecipitation-immunoblot assay. Additional assays included BP180 ELISA and BP230 ELISA. We included the sera of 19 patients with PNP and 40 control subjects.
  
  
  RESULTS
  The sensitivities were 63% for anti-EP ELISA, 74% for rat bladder IIF, 89% for immunoblotting, 95% for radioactive immunoprecipitation and 100% for nonradioactive immunoprecipitation. Specificities ranged from 86% to 100%. The BP180 and BP230 ELISAs had low sensitivity and specificity for PNP. The combination of rat bladder IIF and immunoblot showed 100% sensitivity and specificity. The analysis of sequential PNP sera showed that antibody titres may decrease over time, possibly resulting in negative outcomes for EP ELISA and rat bladder IIF studies.
  
  
  CONCLUSIONS
  The detection of autoantibodies against EP and periplakin, or A2ML1 by immunoprecipitation is most sensitive for PNP. The combination of rat bladder IIF and immunoblotting is equally sensitive and highly specific, and represents an alternative valuable and relatively easy approach for the serological diagnosis of PNP.
authors.affiliation: Department of Dermatology, Center for Blistering Diseases, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: A M
authors.initials: AM
authors.lastname: Poot
authors.forename: G F H
authors.initials: GF
authors.lastname: Diercks
authors.forename: D
authors.initials: D
authors.lastname: Kramer
authors.forename: I
authors.initials: I
authors.lastname: Schepens
authors.forename: G
authors.initials: G
authors.lastname: Klunder
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
authors.forename: L
authors.initials: L
authors.lastname: Borradori
authors.forename: M F
authors.initials: MF
authors.lastname: Jonkman
authors.forename: H H
authors.initials: HH
authors.lastname: Pas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D016022:Case-Control Studies; D019411:Clinical Laboratory Techniques / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D007150:Immunohistochemistry / Q000379:methods; D007159:Immunologic Tests / Q000379:methods; D008297:Male; D008875:Middle Aged; D010257:Paraneoplastic Syndromes / Q000175:diagnosis*; D010392:Pemphigus / Q000175:diagnosis*; D051381:Rats; D012680:Sensitivity and Specificity; D001743:Urinary Bladder / Q000378:metabolism